Cosmic ray intensity affects global warming

IPCC's future prediction of global warming needs a relook since it does not take into account the long-term changes in the galactic cosmic ray intensity, new research says.

In order to estimate the realistic contribution of long-term cosmic ray intensity changes to climate warming, scientists from the Indian Space Research Organisation (ISRO) have compiled data for the last 150 years. The data shows that the radiative forcing component (change in net irradiance at the boundaries between layers of atmosphere) during this period was 1.1 watt per square meter (W/m2). This is due to the decrease in primary cosmic ray intensity.

A decrease in primary cosmic ray intensity results in lesser low cloud cover. The correlation between low-level clouds and primary cosmic ray intensity is well established. Less radiation reflected back into space, due to lesser low cloud cover, results in an increase in the surface temperature on the earth.

The researchers extrapolated the intensity of galactic cosmic radiation using 10Be measurements in deep polar ice as the proxy. The results clearly showed that the primary cosmic ray intensity had decreased by 9% during the last 150 years due to the continuing increase in solar activity.

The researchers conclude that the contribution to climate change due to the change in galactic cosmic ray intensity is quite significant and needs to be factored into the prediction of global warming and its effect on sea level rise and weather prediction.